JPWO2006011197A1 - Encoded data re-encoding device, decoding device and program thereof - Google Patents

Abstract

An encoded data analysis unit 1 for extracting block data and data representing the image characteristics from the encoded image data, a plurality of code tables 4 and 5 each having an optimized code amount for each image characteristic, and encoding A code table selection unit 2 that selects a code table used for re-encoding based on data representing image characteristics extracted by the data analysis unit 1, and a block data is re-encoded using the code table selected by the code table selection unit 2 And a variable-length re-encoding unit 3 that outputs a coded bit stream of encoded data.

Description

  The present invention relates to an encoded data re-encoding device for re-encoding moving image encoded data, a decoding device for the same, and a program for causing a computer to realize them.

  In recent years, a plurality of types of encoding methods have been proposed in order to reduce the amount of information of moving image signals. Some of these methods have already been established as international standard methods. For example, ISO / IEC 13818-2 (MPEG-2) is a typical video encoding method, and is widely adopted in various countries around the world as a video storage method for digital broadcasting and DVD media.

  Recently, a re-encoding method of moving image encoded data for re-encoding the moving image encoded data encoded by MPEG-2 without loss has been studied. For example, there is a method described in Patent Document 1. In the method of Patent Document 1, a variable-length code symbol defined by a coding method as a moving image compression standard is set as a re-encoding target symbol in input encoded data, and the frequency of occurrence of the re-encoding target symbol is determined. Are calculated in predetermined frame units. Then, based on the calculated occurrence frequency, the symbol to be re-encoded in the encoded data may be an arithmetic code, or a variable-length coding table regenerated based on the calculated occurrence frequency may be used. Re-encode.

  In addition, in Patent Document 1, the occurrence frequency of the re-encoding target symbol is calculated for each position of the zigzag scan calculated by decoding the two-dimensional variable length code symbol or for each quantization step, and the calculated occurrence frequency. The video encoded data is re-encoded based on the above.

JP 2001-346212 A

  The conventional technique such as Patent Document 1 discloses only determining a variable length code based on the occurrence frequency of a re-encoding target symbol calculated for each zigzag scan position and each quantization step. There has been a problem that the amount cannot be optimized and re-encoded more efficiently.

  For example, in the conventional technique, it is not possible to perform optimization while suppressing an increase in the code amount according to the image characteristics of each partial region in the image that affects the symbol occurrence probability. For example, when a flat area and a complex texture area are included in a picture, highly efficient re-encoding with the code amount optimized according to the characteristics of each area may be executed. Can not.

  Further, conventionally, it is impossible to re-encode while changing the syntax order of encoded data as necessary. For this reason, for example, even if there is a large deviation for each area in the image, the encoded symbol cannot be used, and high-efficiency re-encoding with an optimized code amount is performed. I can't.

  Furthermore, conventionally, there is no means for removing the I-picture syntax, which is an intra-frame coded picture, for example, although a flag that is not necessarily required when performing the decoding process exists. For this reason, it is not possible to optimize the code amount by removing data that is not used in the decoding process.

  The present invention has been made in order to solve the above-described problems. An encoded data re-encoding device capable of highly efficient re-encoding by optimizing the amount of code, and a code re-encoded in the same. It is an object of the present invention to obtain a decoding device that suitably decodes digitized data, and a program that causes a computer to realize them.

  The encoded data re-encoding device according to the present invention inputs a bit stream of encoded data of a moving image, analyzes the configuration thereof, and encodes the encoded data of the partial region and the partial region in the image constituting the moving image. A coded data analysis unit that extracts data representing image characteristics, and a code table that includes a plurality of code tables in which the amount of codes assigned to the coding target symbols of the coded data in the partial area is optimized for each image characteristic. A code table selection unit that selects a code table to be used for re-encoding the encoded data of the partial region from the code table group, based on the data representing the image characteristics extracted by the group and the encoded data analysis unit; The encoded data in the partial area is re-encoded using the code table selected by the table selection unit, and the bit stream of the encoded data including the re-encoded data is used. It is intended and a re-encoding unit for outputting a beam. Thereby, there is an effect that the code amount can be optimized and highly efficient re-encoding can be realized.

  The decoding device according to the present invention is encoded data of a moving image, and is a bit of data obtained by re-encoding encoded data of a partial region in an image constituting the moving image by the encoded data re-encoding device. A re-encoded data analysis unit that analyzes the structure of the input stream and extracts the encoded data of the re-encoded partial area and the image characteristics of the partial area, and the code of the partial area for each image characteristic A code table based on a code table group composed of a plurality of code tables each optimized in the amount of codes to be allocated to the encoding target symbols of the encoded data, and data representing the image characteristics extracted by the re-encoded data analysis unit A code table selection unit that selects a code table used for re-encoding from the group, and a partial region encoding using the code table selected by the code table selection unit Decoding the over data, and a decoding processing unit for outputting a bit stream of the original encoded data. Thereby, there is an effect that the encoded data re-encoded by changing the symbol for each region can be restored to the original encoded data.

It is a block diagram which shows the structure of the coding data re-encoding apparatus by Embodiment 1 of this invention. It is a table | surface which shows the correspondence of a symbol and the equal length codeword allocated to this. It is a table | surface which shows the correspondence of a symbol and the variable length codeword allocated according to this generation | occurrence | production probability. It is a figure which shows the outline | summary of the syntax of MPEG-2. It is a figure for demonstrating the selection criteria of a variable-length code table. It is a block diagram which shows the structure of the coding data re-encoding apparatus by Embodiment 2 of this invention. It is a block diagram which shows the structure of the decoding apparatus by Embodiment 3 of this invention. It is a block diagram which shows the structure of the decoding apparatus by Embodiment 4 of this invention.

Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
1 is a block diagram showing a configuration of a coded data re-encoding apparatus according to Embodiment 1 of the present invention. The encoded data re-encoding device according to the present embodiment includes an encoded data analysis unit 1, a variable-length code table selection unit (code table selection unit) 2, a variable-length re-encoding unit (re-encoding unit) 3, and a variable A long code table (code table, code table group) 4 and 5 is included. The encoded data analysis unit 1 performs decoding processing of moving image encoded data in accordance with the MPEG-2 standard, and extracts data to be re-encoded from the encoded data.

  The variable length code table selection unit 2 selects a code table having the smallest code amount according to the data to be re-encoded from a plurality of variable length code tables. In the figure and the following description, one of the two types of variable length code tables 4 and 5 is selected. The variable length re-encoding unit 3 re-encodes the moving image encoded data using the variable length code table selected by the variable length code table selecting unit 2.

  In the illustrated example, the case where two types of tables are provided as variable length code tables used for re-encoding has been described as an example. However, the present invention is not limited to this, and three or more types of tables are provided. It may be provided. For example, a variable length code table may be prepared in which an optimal codeword is assigned to each data such as motion vector data and macroblock data described later.

  Here, allocation of codewords to symbols to be encoded will be described. For example, consider a case where codewords are assigned to four symbols (A, B, C, D). FIG. 2 is a table showing a correspondence relationship between symbols to be encoded and equal-length codewords assigned thereto. The code length per symbol of the code word shown in this figure is always 2 bits. This codeword assignment is optimal when the probability of occurrence of all four symbols is equal to 0.25.

  On the other hand, when the deviation of the symbol occurrence probability is known in advance, encoding using a Huffman code that reduces the overall code amount by changing the code length according to the symbol occurrence probability is used. FIG. 3 is a table showing a correspondence relationship between symbols to be encoded and variable-length codewords assigned according to their occurrence probabilities.

  The average code length per symbol is: probability of occurrence of symbol A × bit length of codeword assigned to symbol A + probability of occurrence of symbol B × bit length of codeword assigned to symbol B + probability of occurrence of symbol C × symbol The bit length of the code word assigned to C + the probability of occurrence of the symbol D × the bit length of the code word assigned to the symbol D. In the case of FIG. 3, it is 0.5 × 1 + 0.25 × 2 + 0.125 × 3 + 0.125 × 3 = 1.75 bits. This means that the code amount can be reduced by 0.25 bits from the 2-bit isometric codeword shown in FIG.

  On the other hand, when the occurrence probabilities of the four symbols are all equal to 0.25, the average code length when the code word shown in FIG. 3 is used is 0.25 × 1 + 0.25 × 2 + 0.25 × 3 + 0. 25 × 3 = 2.25 bits. This is because the code amount is increased by 0.25 bits from the 2-bit isometric codeword shown in FIG. Thus, in order to reduce the amount of codes and perform efficient re-encoding, it is necessary to assign an optimal code word according to the symbol occurrence probability.

  Further, the encoded data analysis unit 1, the variable length code table selection unit 2, and the variable length re-encoding unit 3 described above execute the encoded data re-encoding program according to the present invention using, for example, a general-purpose computer. Can be realized.

  More specifically, the encoded data re-encoding program according to the present invention is read by a computer and its operation is controlled, so that the encoded data analyzing unit 1 and variable length code table shown in FIG. The selection unit 2 and the variable length re-encoding unit 3 can be realized. The variable length code tables 4 and 5 can be configured on the storage device of the computer.

  In the following description, the configuration and basic functions of the computer that implements the encoded data re-encoding device of the present invention can be easily recognized by those skilled in the art based on the common general technical knowledge in the field. Since it is not directly related to the essence of the present invention, detailed description is omitted.

  FIG. 4 is a diagram showing an outline of the syntax of MPEG-2. In the following description, it is assumed that the encoded data analysis unit 1 operates according to the MPEG-2 standard. In MPEG-2, video signals are handled in layers. For example, the picture data shown in FIG. 4 is composed of one picture header and a plurality of slice data. The slice data is composed of one slice header and a plurality of macroblock data.

  One macro block is composed of four luminance signal blocks and two kinds of color difference signal blocks. The macro block data is composed of six block data of luminance signal blocks and chrominance signal blocks and information on several macro blocks.

  As described above, the encoded data according to MPEG-2 includes, in addition to header information such as a picture header and a slice header, MAI (Macroblock Address Increment) indicating macroblock position information, which is information related to a macroblock, and macroblock mode information. And macroblock information, and further comprises six block data for each macroblock.

  Note that the macroblock mode information is information about a macroblock including three types of information: a macroblock type, a motion compensation prediction type, and a DCT (Discrete Cosine Transform) block type. Macroblock information is information given to each macroblock, such as motion vector data, quantization parameters (quantization width characteristics), and CBP (Coded Block Pattern) which is a significant block pattern.

Next, the operation will be described.
In the first embodiment, for simplicity of explanation, a case where only block data is to be re-encoded will be described as an example.
First, the encoded data analysis unit 1 analyzes the configuration of the encoded data input as a bitstream by performing a decoding process in accordance with the MPEG-2 standard, and according to the configuration data of the bitstream. Determine the output destination.

  Specifically, for data other than the block data to be re-encoded and not used for re-encoding to be described later, as shown by an arrow leading to the output of the variable-length re-encoding unit 3 in the figure The device output is used as it is. On the other hand, the block data in the input encoded data and the specific data used by the variable length code table selection unit 2 (to be described later) for table selection (for example, motion vector data given to the macroblock) are variable length codes. Output to the table selection unit 2.

  The block data is a transform coefficient obtained by performing two-dimensional DCT on the video signal of each block (in the case of a P picture or B picture, a difference signal between an input signal to be encoded and an encoded prediction reference signal). This is information indicating the texture of each block. For this reason, for example, when a plurality of subjects are shown in a moving image screen, the occurrence frequency of block data symbols for the same subject is relatively uniform, and the occurrence frequency of block data symbols for different subjects tends to vary. It is in.

  Therefore, the variable length code table selection unit 2 performs control so that the allocation of the variable length code tables 4 and 5 used for re-encoding is switched for each subject in the block data when re-encoding the block data. Specifically, for example, the variable length code table selection unit 2 executes the following first to fifth selection processes to switch the variable length code table.

  In the first selection process, a threshold relating to the magnitude of the motion vector assigned to each macroblock is set in advance in the variable length code table selection unit 2. Then, the variable length code table selection unit 2 is provided from the encoded data analysis unit 1 to the block data to be re-encoded (the encoded data of the partial area in the image constituting the moving image) and the macroblock. When a motion vector is input, one of the variable length code tables 4 and 5 is selected for re-encoding according to the comparison result between the motion vector and the threshold value.

  A specific example will be described. In the case of a P picture or B picture for motion compensated prediction, a quantized transform coefficient obtained by performing two-dimensional DCT on the difference signal between the input signal to be encoded and the encoded prediction reference signal Constitute block data. In a region where the change between images arranged in time series constituting a moving image is small, the difference signal is small, and therefore, a block data symbol (quantized transform coefficient) whose occurrence probability is biased to a small value close to 0 and A small motion vector is an encoding target.

  On the other hand, in a region where there is a large change between images, a block data symbol and a large motion vector with a small bias in occurrence probability are to be encoded. The magnitude of the motion vector indicates an image characteristic of a change in image signal between the macroblock regions of images arranged in time series constituting the moving image.

  Therefore, the threshold is determined so that the code amount becomes an increase in the allowable range even if the equal length codeword is assigned. Then, it is determined that the image area of the macroblock specified by the motion vector having a size greater than or equal to the threshold value has an image characteristic that the motion vector is large and the occurrence probability of the encoding target symbol of the block data is small. 2. Select a code table to which the equal length codeword shown in FIG.

  On the other hand, the image area of the macroblock specified by the motion vector less than the above threshold is determined to have a small motion vector and the occurrence probability is biased to a small value close to 0 in the occurrence probability of the symbol to be encoded in the block data. . In this case, as described above, if an equal-length code word is assigned, the code amount increases. Therefore, as a code table corresponding to a motion vector less than the threshold, a code table to which a variable-length code word having the smallest code amount is selected according to the occurrence probability bias as shown in FIG. 3 is selected.

  Also, the threshold for the motion vector is set to two or more, the block data is divided into three or more according to the magnitude of the motion vector, and the image characteristic specified by the magnitude of the motion vector classified by each threshold is supported. A code table is prepared in advance. In this way, it is possible to select an appropriate code table when re-encoding block data classified with a threshold value of two or more.

  Further, the variable length code table selection unit 2 is provided with a configuration capable of dynamically changing and controlling the magnitude of the threshold relating to the motion vector, and a code table is prepared for each range of magnitude changed by changing the threshold. For example, the intensity of the motion of the scene in the encoded moving image is estimated from the motion vector distribution of the already encoded picture, and the threshold is decreased when a scene with a large motion continues.

  In this case, if a code table for assigning, for example, the isometric codeword shown in FIG. 2 is prepared for a motion vector equal to or greater than the threshold value, the code table is changed by changing the threshold value when a scene with a large motion continues. Becomes easier to select. In this way, it is possible to flexibly cope with the temporal change of the image signal characteristics in the partial area in the image constituting the moving image.

  The variable length coding unit 3 re-encodes block data constituting the macroblock using the variable length code table selected by the variable length code table selection unit 2 for the macroblock as described above. It will be. In this case, the selection of the variable length code table is uniquely determined by the magnitude of the motion vector.

  Further, when decoding the re-encoded moving image encoded data, the size of the motion vector is obtained from the motion vector data shown in FIG. 4, and the code table used for re-encoding can be specified. For this reason, it is not necessary to add information specifying which code table is selected in the re-encoding to the re-encoded moving image encoded data.

  In the second selection process, a threshold relating to the number of symbols of block data to be re-encoded is set in advance in the variable-length code table selection unit 2. Then, the encoded data analysis unit 1 analyzes the input encoded data, obtains the number of block data and its symbols, and outputs them to the variable length code table selection unit 2.

  The variable length code table selection unit 2 selects one of the variable length code tables 4 and 5 for re-encoding according to the comparison result between the number of the symbols and the threshold value.

  Note that the number of symbols of the block data is not set by the syntax of the moving image encoded data as shown in FIG. That is, when decoding the re-encoded moving image encoded data, the code table used for re-encoding cannot be specified from the moving image encoded data.

  Therefore, the variable length re-encoding unit 3 adds information for specifying the code table selected by re-encoding to the re-encoded moving image encoded data. As a method of adding information for specifying the code table selected by re-encoding, for example, it is added as a part of picture header, slice header, macro block mode information, etc. in the re-encoded moving image encoded data. Can be mentioned.

  The block data usually contains only about 1 to several symbols in a flat area on the screen, but contains many symbols in an area having a complex texture. Depending on the number of symbols, the frequency of occurrence of symbols to be encoded also differs.

  For this reason, it is possible to efficiently perform the re-encoding process by selecting an appropriate variable-length code table according to the number of generated symbols. Thus, the number of symbols can be an index for knowing image characteristics such as whether a partial area specified by each block data of an image is flat or has a complex texture.

  In the third selection process, a threshold relating to the value of the DC component of the DCT coefficient in the block data to be re-encoded is set in the variable length code table selection unit 2 in advance. Then, the encoded data analysis unit 1 analyzes the input encoded data, obtains block data and the value of its DC component, and outputs the block data and the DC component value to the variable length code table selection unit 2.

  The variable length code table selection unit 2 changes the variable length code according to the comparison result between the difference value between the DC component in the region specified by the block data to be recoded and the DC component in the surrounding region, and the threshold value. One of the tables 4 and 5 is selected for re-encoding.

  The variable length re-encoding unit 3 performs block data re-encoding processing using the variable length code table selected by the variable length code table selecting unit 2 as described above. In the MPEG-2 standard, the encoding process of the DC component of the block data is different from the encoding process of the AC component.

  That is, when decoding the re-encoded video encoded data, the DC component value is extracted from the video encoded data, and the variable length code table selection process is uniquely determined. For this reason, it is not necessary to give information on which code table is selected to the re-encoded moving image encoded data.

  It is often the case that regions having the same DC component value in an image have the same brightness and color. For this reason, the value of the DC component indicating the light / dark / color state can be an index representing the image characteristics of the partial area in the image.

  In the fourth selection process, the variable length code table selection unit 2 actually generates a code amount using all or two or more of the plurality of variable length code tables to be selected for re-encoding. And the variable length code table with the smallest code amount is selected. In this case, since it is necessary to perform variable-length encoding processing once, the amount of processing in re-encoding increases, but a variable-length code table with the highest encoding efficiency can be selected.

  In this selection process, the variable length code table selection unit 2 selects a code table based on the amount of code actually generated. For this reason, when decoding the re-encoded moving image encoded data, the variable length code table selected for re-encoding from the moving image encoded data cannot be specified.

  Therefore, similarly to the second selection process, the variable-length code table selection unit 2 separately assigns information for specifying the code table selected for re-encoding to the re-encoded moving image encoded data.

  In the fifth selection process, the encoded data analysis unit 1 measures the symbol occurrence frequency in the block data. A plurality of code tables that provide optimum code amounts are prepared in advance according to the occurrence frequency patterns of a plurality of symbols.

  The variable length code table selection unit 2 sequentially inputs the occurrence frequency of symbols in the block data from the encoded data analysis unit 1, and determines whether or not the pattern of the occurrence frequency is suitable for the currently selected variable length code table. judge.

  For example, a relationship between a symbol occurrence frequency pattern and a code table that gives an optimum code amount is obtained in advance by actual encoding, and a code table according to this relationship is provided. In addition, the variable length code table selection unit 2 registers a symbol occurrence frequency pattern in association with the code table.

  Then, the variable length code table selection unit 2 compares the symbol occurrence frequency pattern corresponding to the currently selected variable length code table with the symbol occurrence frequency pattern input from the encoded data analysis unit 1 to obtain the code It is determined whether the symbol occurrence frequency pattern input from the digitized data analysis unit 1 is suitable for the currently selected variable-length code table.

  Thus, if it is determined that the code table is suitable for the currently selected code table, the variable-length code table selection unit 2 selects the currently selected variable-length code table as it is for re-encoding.

  On the other hand, if it is determined that the variable length code table is not suitable for the currently selected variable length code table, the variable length code table selection unit 2 registers in advance with the symbol occurrence frequency pattern input from the encoded data analysis unit 1. The optimum variable length code table is determined based on the comparison result with the symbol occurrence frequency pattern, and the selection is switched to the code table.

  For example, in the partial area where the deviation that the code data symbol generation frequency of the block data input from the encoded data analysis unit 1 has many small symbols such as ± 1 and ± 2 occurs is specified in the block data. Consider the case of an observed frequency pattern.

  In this case, the variable-length code table selection unit 2 selects a code table using variable-length code words corresponding to the occurrence probabilities as shown in FIG. On the other hand, if the occurrence frequency pattern is such that every symbol is generated at substantially the same frequency, the variable-length code table selection unit 2 selects a code table using an equal-length code word as shown in FIG.

  The frequency of occurrence of the symbol of the block data is read from the block data of the re-encoded moving image encoded data when the re-encoded moving image encoded data is decoded, and the variable length code table is selected. Processing is uniquely determined. For this reason, it is not necessary to add the information indicating which code table is selected to the re-encoded moving image encoded data.

  In the above-described example, the case where the variable length code table selection process is performed in units of blocks has been described. However, the configuration is such that the data representing the image characteristics as described above is extracted in units of macroblocks or slices and the selection process is performed. May be.

  In addition, when information specifying which code table is selected is separately provided, a flag for identifying the code table may be provided for each block, macroblock, or slice.

  Furthermore, as information for specifying which code table is selected in re-encoding, for example, the following information may be adopted. FIG. 5 is a diagram for explaining selection criteria for the variable-length code table, and shows one screen of encoded data to be re-encoded. As shown in the figure, the screen 6 is divided into a plurality of rectangular areas, and data representing image characteristics is extracted from the image data for the area 7 composed of the plurality of rectangular areas hatched in the screen 6.

  A case is considered in which variable length code table selection processing is executed using data representing the image characteristics. In this case, the variable length code table uniquely selected by the position of the region 7 can be determined. Therefore, only the position information of the upper left and lower right rectangular areas constituting the area 7 may be adopted as information specifying the code table.

  Even when the information for specifying the selected code table is not necessary as in the first, third, and fifth selection processes, information for specifying the code table is separately added to the re-encoded moving image encoded data. It doesn't matter.

  As described above, according to the first embodiment, the encoded data analysis unit 1 that inputs the bit stream of the encoded data of the moving image, analyzes the configuration, and extracts the data representing the block data and the image characteristics; The variable length code tables 4 and 5 in which the code amount allocated to the encoding target symbol of the block data is optimized for each image characteristic, and the image characteristics of the block data extracted by the encoded data analysis unit 1 are represented. A code table selection unit 2 for selecting a variable length code table used for re-encoding based on data, and a block obtained by re-encoding and re-encoding block data using the variable-length code table selected by the code table selection unit 2 And a variable-length re-encoding unit 3 that outputs a bit stream of encoded data including data, and thus a partial region in an image constituting a moving image A coded data, by re-encoding target block data occupies most of the video encoded data can be selected variable length code table in response to the signal characteristics of the partial region in an image. Thereby, moving image coding data can be efficiently re-encoded. For example, MPEG-2 standard encoded data can be efficiently re-encoded according to the characteristics of each region in the picture.

  In the first embodiment, the first to fifth selection processes have been described separately. However, the variable length code table is selected by sequentially executing the first to fifth selection processes. Also good.

Embodiment 2. FIG.
In the first embodiment, an example in which block data in moving image encoded data is re-encoded as an encoding target has been described. In the second embodiment, slice headers and macroblock configuration data in moving image encoded data are re-encoded as encoding targets.

  FIG. 6 is a block diagram showing a configuration of a moving image encoded data re-encoding device according to Embodiment 2 of the present invention. The re-encoding device according to the second embodiment includes an encoded data analysis unit 1, a variable length re-encoding unit 3, an encoded data conversion unit 8, an MAI data memory 9, an MB type data memory 10, and a DCT type data memory 11. , A quantization parameter data memory 12, a CBP data memory 13, and a block data memory 14.

  The encoded data analysis unit 1 decodes moving image encoded data in accordance with the MPEG-2 standard, and extracts data to be re-encoded from the encoded data. The variable length re-encoding unit 3 performs re-encoding on the moving image encoded data to be re-encoded input from the encoded data conversion unit 8.

  Note that, unlike the first embodiment, the variable length re-encoding unit 3 according to the second embodiment performs arithmetic coding instead of the variable length code table. The encoded data conversion unit 8 performs conversion processing such as symbol deletion or replacement on the moving image encoded data to be re-encoded.

  The MAI data memory 9 stores MAI data. The MB type data memory 10 stores macro block type data. The DCT type data memory 11 stores DCT block type data. The quantization parameter data memory 12 stores quantization parameter data. The CBP data memory 13 stores CBP data. The block data memory 14 stores block data.

  The encoded data analysis unit 1, the encoded data conversion unit 8, and the variable length re-encoding unit 3 described above are realized by executing the encoded data re-encoding program according to the present invention using, for example, a general-purpose computer. it can.

  More specifically, the encoded data re-encoding program according to the present invention is read by a computer and its operation is controlled, so that the encoded data analysis unit 1 shown in FIG. The unit 8 and the variable length re-encoding unit 3 can be realized. Further, the memories 9 to 14 can be configured on the storage device of the computer.

  In the following description, the configuration and basic functions of the computer that implements the encoded data re-encoding device of the present invention can be easily recognized by those skilled in the art based on the common general technical knowledge in the field. Since it is not directly related to the essence of the present invention, detailed description is omitted.

Next, the operation will be described.
First, the encoded data analysis unit 1 performs a decoding process in accordance with the MPEG-2 standard on encoded data input as a bit stream, analyzes the configuration, and re-encodes the extracted extracted from the bit stream. The target encoded data is output to the encoded data conversion unit 8. At this time, for the conversion process by the encoded data conversion unit 8, the encoded data analysis unit 1 appropriately stores the data to be converted in the corresponding memories 9 to 14 and then outputs the data to the encoded data conversion unit 8. .

  The encoded data conversion unit 8 re-encodes the encoded data from the configuration data of the moving image encoded data input from the encoded data analysis unit 1 and then decodes the encoded data to the original encoded data compliant with the MPEG standard. Delete unnecessary data or replace it with data with a small amount of information. Specifically, for example, the following first to third conversion processes are executed.

  First, in the first conversion process, the encoded data conversion unit 8 deletes the slice header from the constituent data of the re-encoding target moving image encoded data input from the encoded data analysis unit 1.

  The MPEG slice header is set to recover from an error state when an error originally occurs. For this reason, it is unnecessary for an application that does not need to assume the occurrence of an error as in the case of reproducing moving image encoded data from a storage medium. Therefore, the encoded data conversion unit 8 deletes the slice header. As a result, in each slice of the encoded data, a macro block is arranged at the position of the slice header, and the syntax order is changed.

  In the second conversion process, if the picture to be re-encoded of the moving image encoded data input from the encoded data analysis unit 1 by the encoded data conversion unit 8 is an I picture, the MAI data in the macroblock is converted. delete. In an I picture for which only intraframe coding processing is performed, MAI data always takes a value of “1”.

  Such data having always the same value can be uniquely processed in the restoration process for the re-encoded encoded data. Therefore, the encoded data conversion unit 8 deletes the MAI data when the picture to be re-encoded is an I picture. Thereby, in each macroblock of the encoded data, the macroblock type data is arranged at the position of the MAI data, and the syntax order is changed.

  On the other hand, for picture types such as P pictures and B pictures, MAI data takes a value other than “1”. The value of MAI data generally corresponds to the presence / absence of movement in the screen and the state of texture. That is, in the P picture and B picture, the value of MAI data tends to be unevenly distributed in the screen.

  Therefore, when the picture type is a P picture or a B picture, the following processing is performed using the fact that arithmetic coding is a coding method having a higher compression effect as the generation distribution of encoding target symbols is biased. I do.

  First, when the encoded data analysis unit 1 determines that the picture type is a P picture or a B picture by analyzing the input moving image encoded data to be encoded, the MAI data in the encoded data Only one screen is extracted and one screen portion is sequentially stored in the MAI data memory 9.

  In the variable length re-encoding unit 3, the MAI data in which one screen is sequentially stored is read from the MAI data memory 9 through the encoded data analysis unit 1 and the encoded data conversion unit 8, and is re-encoded by arithmetic encoding. Turn into.

  As described above, arithmetic coding can be performed after increasing the bias in the screen by combining only the MAI data whose generation distribution tends to be biased in the screen into one screen. As a result, it is possible to realize highly efficient re-encoding by making use of the uneven distribution of MAI data generation within one screen.

  In the third conversion process, when the picture to be re-encoded by the encoded data converter 8 from the encoded data analyzer 1 is an I picture, the macroblock type data symbol Of these, “01” is replaced with “0” having a smaller amount of information.

  For an I picture that only performs intra-frame coding processing, the macroblock type data always takes only a symbol of “1” or “01”. This is for consistency with decoding processing in other picture types (P picture and B picture).

  In this case, if only the I picture is considered, it is possible to uniquely decode two symbols “1” and “0”. Therefore, when the picture to be re-encoded is an I picture, the encoded data conversion unit 8 replaces the “01” symbol of the macroblock type data with “0”.

  On the other hand, the distribution of macroblock type data also tends to be biased within the screen, as described for the MAI data in the second conversion process. Therefore, if the picture type is a P picture or a B picture, the encoded data analysis unit 1 extracts only macroblock type data and sequentially stores one screen in the MB type data memory 10.

  The variable length re-encoding unit 3 reads out the macroblock type data in which one screen is sequentially stored from the MB type data memory 10 via the encoded data analysis unit 1 and the encoded data conversion unit 8 and performs arithmetic encoding. Then, re-encoding is executed.

  As described above, only macroblock type data whose occurrence distribution tends to be biased within the screen is subjected to encoding for one screen at a time, and arithmetic coding can be performed while increasing the bias within the screen. it can. As a result, it is possible to realize a highly efficient re-encoding process by taking advantage of the occurrence distribution of macroblock data in one screen.

In addition to the above-described data conversion process, the data memory 11 to 14 is used to execute a re-encoding process that makes use of the bias of the generation distribution to be encoded.
For example, DCT block type data always takes a symbol of “1” or “0” regardless of the picture type of the moving image encoded data. As for the DCT block type data, the occurrence distribution tends to be biased in the screen as in the case of MAI data and macro block type data.

  Therefore, the encoded data analysis unit 1 extracts only DCT block type data in the encoded data by analyzing the input moving image encoded data to be re-encoded, and DCT block type data for one screen. Are sequentially stored in the DCT type data memory 11.

  The variable length re-encoding unit 3 collectively reads out DCT block type data in which one screen is sequentially stored from the DCT type data memory 11 via the encoded data analysis unit 1 and the encoded data conversion unit 8 and performs arithmetic encoding. Then, re-encoding is executed.

  As described above, only DCT block type data whose occurrence distribution tends to be biased in the screen is subjected to encoding for one screen at a time, and arithmetic coding can be performed after increasing the bias in the screen. it can. As a result, it is possible to realize a highly efficient re-encoding process by making use of the bias in the distribution of DCT block type data within one screen.

  Similarly, for the quantization parameter data and CBP data, the encoded data analysis unit 1 sequentially stores one screen in the quantization parameter data memory 12 and the CBP data memory 13, and the variable length re-encoding unit 3 respectively These data may be re-encoded together.

  Further, the block data memory 14 may also be used to store all the data of the macro block type data for one screen and re-encode the data for each data collectively.

  That is, the encoded data analysis unit 1 analyzes the input moving image encoded data to be re-encoded, and thereby, MAI data, macroblock type data, DCT block type data, quantization parameter data, and CBP data in the macroblock. , And block data are extracted, and one screen of these data is sequentially stored in the data memories 9-14.

  The variable-length re-encoding unit 3 reads out each data sequentially stored for one screen from the data memories 9 to 14 via the encoded data analysis unit 1 and the encoded data conversion unit 8, and re-reads it by arithmetic encoding. Perform encoding.

  In the above-described processing, an example is shown in which one screen is stored in one of the memories 9 to 14 corresponding to the encoding target data. However, when the data is not used together with the first conversion processing, that is, the slice header If not removed, slice units may be re-encoded together.

  Further, in combination with the configuration of the first embodiment, it is possible to read and re-encode data stored in the memories 9 to 14 in units of areas in the screen.

  For example, the variable length code table selection unit 2 according to the first embodiment is provided between the encoded data conversion unit 8 and the variable length re-encoding unit 3 in the second embodiment shown in FIG. The re-encoding unit 3 is configured to include a plurality of variable length code tables.

  In this configuration, the encoded data analysis unit 1 extracts, for example, all block data in a macro block and its motion vector by analyzing the input moving image encoded data to be re-encoded, and saves one screen. The data is sequentially stored in the block data memory 14.

  When the variable length code table selection unit 2 inputs block data for one screen and a motion vector assigned to the macroblock from the block data memory 14 via the encoded data analysis unit 1, the motion vector for each block data is input. The variable length code table is selected according to the comparison result between the threshold value and the threshold value. The variable length re-encoding unit 3 re-encodes the block data for one screen using the variable length code table selected by the variable length code table selection unit 2.

  As described above, according to the second embodiment, the encoded data analysis unit 1 that inputs the bit stream of the encoded data of the moving image, analyzes the configuration thereof, and extracts the configuration data of the encoded data; A plurality of memories 9 to 14 for storing each component data of the encoded data extracted by the encoded data analysis unit 1; and deleting data not used in the decoding process for the component data of the encoded data and / or Alternatively, the encoded data conversion unit 8 replaces the encoding target symbol of the configuration data with digital data having a smaller amount of information, and reads the configuration data of the encoded data from the memories 9 to 14 and re-encodes the data to be re-encoded. And a variable-length re-encoding unit 3 that outputs a bit stream of encoded data including the re-encoded data. Or deleting unnecessary data at the time of decoding that are included, or replace redundant symbols to a small data amount of information, it is possible to efficiently re-encoding by encoding together various symbols.

Embodiment 3 FIG.
FIG. 7 is a block diagram showing a configuration of a decoding apparatus according to Embodiment 3 of the present invention, and shows a case where moving image encoded data obtained by re-encoding block data is decoded. The decoding apparatus according to the present embodiment includes a re-encoded data analysis unit 1a, a variable-length code table selection unit 2a, an encoded data restoration unit 15, and variable-length code tables 4 and 5.

  The re-encoded data analysis unit 1a analyzes, for example, the moving image encoded data re-encoded by the encoded data re-encoding device of the first embodiment, and the re-encoding target is re-encoded from the encoded data. Extract data. The variable length code table selection unit 2a selects a code table used for the re-encoding from a plurality of variable length code tables based on the decoding target data input from the re-encoded data analysis unit 1a.

  In the figure and the following description, it is assumed that the encoded data to be decoded has been re-encoded with one of the two types of variable-length code tables 4 and 5. Note that three or more types of variable length code tables may be provided. The encoded data restoration unit 15 decodes moving image encoded data in accordance with the MPEG-2 standard using the variable length code table selected by the variable length code table selection unit 2a.

  In addition, the re-encoded data analysis unit 1a, the variable-length code table selection unit 2a, and the encoded data restoration unit 15 can be implemented by executing a decoding processing program according to the present invention using, for example, a general-purpose computer.

  More specifically, the decoding program according to the present invention is read by a computer and its operation is controlled, whereby the re-encoded data analysis unit 1a and the variable-length code table selection unit 2a shown in FIG. The encoded data restoration unit 15 can be realized. The variable length code tables 4 and 5 can be configured on the storage device of the computer.

  In the following description, the configuration of the computer itself that embodies the decoding device of the present invention and the basic functions thereof can be easily recognized by those skilled in the art based on the common general technical knowledge in the field. Detailed description is omitted because it is not directly related to the essence of.

Next, the operation will be described.
In the third embodiment, for the sake of simplicity, block data is re-encoded, and a case where this is decoded will be described as an example.
First, the re-encoded data analysis unit 1a inputs moving image encoded data in which block data is re-encoded by the re-encoding device according to the first embodiment, and MPEG- Decoding processing according to the standard No. 2 is performed, the configuration is analyzed, and an output destination corresponding to the configuration data is determined.

  Specifically, data other than the re-encoded block data that is not used for the decoding process described later is directly output from the apparatus as indicated by an arrow leading to the output of the encoded data restoration unit 15 in the figure. And

  On the other hand, re-encoded block data in the input encoded data and specific data (for example, motion vector data assigned to a macro block) used by the variable-length code table selection unit 2a described later for table selection Is output to the variable length code table selection unit 2a.

  The variable length code table selection unit 2a controls to switch the assignment of the variable length code tables 4 and 5 used for the block data decoding for each subject in the block data. Specifically, for example, the variable length code table selection unit 2a executes the following first to fifth selection processes to switch the variable length code table.

  In the first selection process, a threshold value relating to the magnitude of a motion vector given to a macroblock having re-encoded block data as a constituent element and a DC component value of a DCT coefficient in the block data (the above embodiment). 1 is set in advance in the variable length code table selection unit 2a.

  In addition, a variable length code table corresponding to each of the motion vector having a magnitude smaller than the threshold and a threshold greater than the threshold is prepared. In the variable length code table selection unit 2a, the magnitude of the motion vector input from the re-encoded data analysis unit 1a and the difference value between the DC component of the area specified by the block data to be processed and the DC component of the surrounding area Then, the variable length code table to be selected for the block data is determined from the comparison result with the threshold value.

  If the threshold value is set to two or more values in the re-encoding device that re-encodes the block data, the threshold value is set in the variable-length code table selection unit 2a in the same manner. Also, a code table classified according to each threshold is prepared in advance. Even in this way, it is possible to select an appropriate code table for decoding block data classified with a threshold value of two or more.

  Further, the variable length code table selection unit 2a is provided with a configuration capable of dynamically changing and controlling the magnitude of the threshold value, and a code table is prepared for each range of magnitude that is changed by changing the threshold value. Thus, the code table that would have been selected by the re-encoding device can be selected by appropriately changing and controlling the threshold of the moving vector.

  The second selection process is a case where block data is re-encoded based on the number of symbols and the code amount generated in the actual encoding process by the re-encoding device of the first embodiment. This is a case where information indicating a code table used for re-encoding is included in the encoded moving image encoded data.

  In this case, the re-encoded data analysis unit 1a performs, for example, a part of the picture header, slice header, macro block mode information, etc. of the re-encoded moving image encoded data, or in the screen 6 shown in FIG. Information specifying the code table used for re-encoding, which is given in units of rectangular information, is extracted and output to the variable-length code table selection unit 2a. The variable length code table selection unit 2a selects a code table using information for specifying the code table.

  As described above, when the variable length code table selection unit 2a selects the variable length code table used for re-encoding the block data, the selection result is output to the encoded data restoration unit 15. The encoded data restoration unit 15 decodes the block data using the selected variable length code table and outputs moving image encoded data in accordance with the MPEG-2 standard.

  As described above, according to the third embodiment, the bit stream of the encoded data of the moving image in which the block data is re-encoded by the re-encoding device according to the first embodiment is input and the configuration is analyzed. A re-encoded data analysis unit 1a for extracting data representing the block data and image characteristics, and a variable-length code table in which the code amount of codes allocated to the encoding target symbols of the block data is optimized for each image characteristic 4 and 5, a code table selection unit 2a for selecting a variable length code table used for re-encoding based on data representing image characteristics extracted by the re-encoded data analysis unit 1a, and a code table selection unit 2a An encoded data restoration unit 15 that decodes block data using the selected variable-length code table and outputs a bit stream of the original encoded data; Since it is provided, even block data that is encoded data of each partial area is decoded even if the encoded data is re-encoded by changing the symbol for each partial area in the image constituting the moving image. Thus, it is possible to restore the original encoded data of the MPEG-2 standard.

Embodiment 4 FIG.
FIG. 8 is a block diagram showing a configuration of a decoding apparatus according to Embodiment 4 of the present invention, and shows a case where moving image encoded data obtained by re-encoding slice header and macroblock configuration data is decoded. . The decoding apparatus according to the fourth embodiment includes a re-encoded data analyzing unit 1a, an encoded data inverse converting unit 16, an encoded data restoring unit 15, an MAI data memory 9a, an MB type data memory 10a, a DCT type data memory 11a, It includes a quantization parameter data memory 12a, a CBP data memory 13a, and a block data memory 14a.

  The re-encoded data analysis unit 1a analyzes, for example, the moving image encoded data re-encoded by the encoded data re-encoding device of the first embodiment, and the re-encoding target is re-encoded from the encoded data. Extract data. The encoded data restoration unit 15 performs a decoding process on the encoded data to be decoded input from the encoded data inverse conversion unit 16.

  In the following description, the re-encoded data to be decoded is re-encoded by arithmetic encoding instead of the variable-length code table by the re-encoding device of the second embodiment. And The encoded data inverse conversion unit 16 performs an inverse conversion process of adding a symbol deleted from the moving image encoded data re-encoded by the re-encoding device of the second embodiment or replacing the original symbol with the original symbol. To do.

  The MAI data memory 9a stores MAI data. The MB type data memory 10a stores macro block type data. The DCT type data memory 11a stores DCT block type data. The quantization parameter data memory 12a stores quantization parameter data. The CBP data memory 13a stores CBP data. The block data memory 14a stores block data.

  The re-encoded data analysis unit 1a, the encoded data inverse conversion unit 16, and the encoded data restoration unit 15 described above can be realized by executing a decoding processing program according to the present invention using, for example, a general-purpose computer.

  In more detail, the decoding processing program according to the present invention is read by a computer and the operation thereof is controlled, whereby the re-encoded data analyzing unit 1a and the encoded data inverse converting unit 16 shown in FIG. The encoded data restoration unit 15 can be realized. Further, the memories 9a to 14a can be configured on the storage device of the computer.

  In the following description, the configuration of the computer itself that embodies the decoding device of the present invention and the basic functions thereof can be easily recognized by those skilled in the art based on the common general technical knowledge in the field. Detailed description is omitted because it is not directly related to the essence of.

Next, the operation will be described.
Thereafter, various encoded data (MAI data, macroblock type data, DCT block type data, quantization parameter data, CBP data, block data) constituting the recoded moving image encoded data is, for example, one picture. An example will be described in which encoded data that has been re-encoded in units of predetermined units such as minutes or one slice is restored.

  First, the re-encoded data analysis unit 1a analyzes the configuration of the moving image encoded data re-encoded by the re-encoding device of the second embodiment, and converts various encoded data into predetermined units (for example, 1 Pictures or one slice) are extracted and stored in the memories 9a to 14a, respectively.

  When the storage of all the encoded data for a predetermined unit in the memories 9a to 14a is completed, the encoded data restoration unit 15 stores these data in the memories 9a to 9 so as to be in order according to the MPEG-2 standard. 14a, respectively, and output a bit stream in accordance with the MPEG-2 standard.

  As a result, it is possible to restore the moving image encoded data in which the individual encoded data is re-encoded for a predetermined unit to the original bit stream.

  The encoded data inverse transform unit 16 determines whether or not various encoded data are re-encoded by deleting or replacing symbols when the encoded data restoring unit 15 reads various encoded data from the memories 9a to 14a. If a symbol is deleted or replaced, a process for restoring it is executed.

  For example, when re-encoded data from which the slice header has been deleted by the re-encoding device of the second embodiment is input, the encoded data inverse transform unit 16 inserts a slice header for each predetermined unit. The encoded data restoration unit 15 outputs the bit stream in accordance with the MPEG-2 standard.

  When re-encoded data from which all the MAI data of the I picture has been deleted is input by the re-encoding device of the second embodiment, the encoded data inverse transform unit 16 performs the MAI data for each macroblock. Is output to the encoded data restoration unit 15 as a bit stream in accordance with the MPEG-2 standard.

  Further, the encoded data inverse conversion unit 16 is set with normal values according to the MPEG-2 standard for the symbols of various encoded data, and the various encoded data to be decoded are re-encoded by replacing the symbols. If it has been converted, the restoration processing to replace with the original symbol is executed.

  For example, when re-encoded encoded data in which “01” is replaced with “0” among the symbols of the macro block type data of the I picture is input, the encoded data inverse transform unit 16 performs the macro block type data Of these symbols, “0” is replaced with “01” and output to the encoded data restoring unit 15 as a bit stream in accordance with the MPEG-2 standard.

  Similarly, even when the symbols of other encoded data are replaced and re-encoded, the encoded data inverse conversion unit 16 performs the replacement by comparing with the normal value set in itself. Judge and replace with the original symbol.

  As described above, according to the fourth embodiment, a bit stream obtained by re-encoding the encoded data of moving image encoded data is input, the configuration is analyzed, and the encoded data of the encoded data is extracted. The re-encoded data analyzing unit 1a, the memories 9a to 14a for storing the respective constituent data of the encoded data extracted by the re-encoded data analyzing unit 1a, and the decoding process for the constituent data of the encoded data It is determined whether or not processing for deleting unused data and / or processing for replacing symbols to be encoded in configuration data with digital data having a smaller amount of information has been performed. The encoded data inverse conversion unit 16 that performs conversion processing to return to the data, and the component data of the encoded data read from the memories 9a to 14a and re-encoded. And the encoded data restoration unit 15 that outputs the bit stream of the original encoded data, the deleted data and the replaced symbols are restored or encoded together. By returning various symbols for each original macroblock, it is possible to restore MPEG-2 standard encoded data.

  In the above embodiment, the description has been given using MPEG-2 as the image encoding method. However, other encoding methods having the same configuration, such as ISO / IEC MPEG-1 and MPEG, are used. -4, H. of ITU-T. 261 and H.264. It is also possible to apply to H.263.

  As described above, the encoded data re-encoding device according to the present invention re-encodes according to the image characteristics of the partial area in the image constituting the moving image extracted from the encoded data of the moving image. For example, MPEG-2, MPEG-1, MPEG-4, and ITU-T H.264 can be efficiently re-encoded. 261 and H.264. It can be suitably used for image compression in various encoding systems such as H.263.

Claims (15)

Encoding data that inputs a bit stream of encoded data of a moving image, analyzes the configuration thereof, and extracts encoded data of a partial region in the image constituting the moving image and data representing the image characteristics of the partial region An analysis unit;
A code table group consisting of a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area for each image characteristic is optimized,
A code table selection unit that selects a code table to be used for re-encoding the encoded data of the partial region from the code table group based on the data representing the image characteristics extracted by the encoded data analysis unit;
A re-encoding unit that re-encodes the encoded data of the partial area using the code table selected by the code table selection unit and outputs a bit stream of the encoded data including the re-encoded data. Data re-encoding device. The encoded data analysis unit extracts motion vector data about a partial region in an image constituting a moving image from the bit stream of the input encoded data,
The code table group includes a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic specified by the magnitude of the motion vector,
The code table selection unit selects a code table used for re-encoding the encoded data of the partial area from the code table group based on the size of the motion vector extracted by the encoded data analysis unit. The encoded data re-encoding device according to claim 1. The encoded data analysis unit extracts the DC component data of the discrete cosine transform coefficient for the partial area in the image constituting the moving image from the input encoded data bit stream,
The code table group includes a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic specified by the DC component data,
The code table selection unit selects a code table used for re-encoding the encoded data of the partial region from the code table group based on the magnitude of the DC component extracted by the encoded data analysis unit. The encoded data re-encoding device according to claim 1.   The re-encoding unit includes information specifying the code table selected by the code table selection unit in a part of a bit stream of encoded data including the re-encoded data, and outputs the information. The encoded data re-encoding device described. An encoded data analysis unit that inputs a bit stream of encoded data of a moving image, analyzes the configuration thereof, and extracts configuration data of the encoded data;
A storage unit group consisting of a plurality of storage units each storing each component data of the encoded data extracted by the encoded data analysis unit;
A data conversion unit that executes processing for deleting data that is not used for decoding processing thereof and / or processing for replacing the configuration data with digital data having a smaller amount of information with respect to the configuration data of the encoded data;
Re-encoding that reads each component data of the encoded data from each storage unit of the storage unit group, re-encodes the data to be re-encoded, and outputs a bit stream of the encoded data including the re-encoded data And a coded data re-encoding device. When the encoded data analysis unit extracts the configuration data of the encoded data, the encoded data analysis unit sequentially stores the configuration data in the storage unit corresponding to the configuration data of the storage unit group,
6. The encoded data re-encoding apparatus according to claim 5, wherein the re-encoding unit reads and re-encodes a plurality of pieces of configuration data stored in each storage unit of the storage unit group. . A bit stream of data that is encoded data of a moving image, and is obtained by re-encoding encoded data of a partial area in the image constituting the moving image by the encoded data re-encoding device according to claim 1. A re-encoded data analysis unit that analyzes the configuration and extracts re-encoded encoded data of the partial region and data representing image characteristics of the partial region;
A code table group consisting of a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area for each of the image characteristics is optimized,
A code table selection unit that selects a code table used for re-encoding from the code table group based on the data representing the image characteristics extracted by the re-encoded data analysis unit;
A decoding apparatus comprising: a decoding processing unit that decodes the encoded data of the partial area using the code table selected by the code table selecting unit and outputs a bit stream of the original encoded data. The re-encoded data analysis unit extracts motion vector data for a partial region in an image constituting the moving image from the re-encoded bit stream of the encoded data,
The code table group includes a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic specified by the magnitude of the motion vector,
The code table selection unit selects a code table used for re-encoding from the code table group based on the size of the motion vector extracted by the re-encoded data analysis unit. Item 8. A decoding device according to Item 7. The re-encoded data analysis unit extracts DC component data of discrete cosine transform coefficients for partial regions in the image constituting the moving image from the re-encoded bit stream of the encoded data,
The code table group includes a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic specified by the magnitude of the DC component,
The code table selection unit selects a code table used for re-encoding the block data to be decoded from the code table group based on the size of the DC component extracted by the re-encoded data analysis unit. The decoding device according to claim 7. When the re-encoded data analysis unit includes information for identifying the code table used for re-encoding as part of the bit stream of the re-encoded encoded data, the re-encoded data analyzing unit displays information for identifying the code table. Extract and
8. The decoding apparatus according to claim 7, wherein the code table selection unit selects a code table used for decoding from a code table group based on information specifying the code table. The encoded data re-encoding device according to claim 5 inputs a bit stream of encoded data of a moving image in which the configuration data is re-encoded, analyzes the configuration, and extracts the configuration data of the encoded data A re-encoded data analysis unit;
A storage unit group composed of a plurality of storage units each storing each piece of configuration data of the encoded data extracted by the re-encoded data analysis unit;
The encoded data re-encoding device performs a process of deleting data not used for the decoding process and / or a process of replacing the structural data with digital data having a smaller amount of information. If so, a data reverse conversion unit that performs a conversion process to return these to the original data,
A decoding processing unit including: a decoding processing unit that reads out the configuration data of the encoded data from each storage unit of the storage unit group, decodes the re-encoded configuration data, and outputs a bit stream of the original encoded data apparatus. Encoding data that inputs a bit stream of encoded data of a moving image, analyzes the configuration thereof, and extracts encoded data of a partial region in the image constituting the moving image and data representing the image characteristics of the partial region Analysis department,
A code table group consisting of a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic;
A code table selection unit that selects a code table to be used for re-encoding the encoded data of the partial region from the code table group based on the data representing the image characteristics extracted by the encoded data analysis unit;
The computer is caused to function as a re-encoding unit that re-encodes the encoded data of the partial area using the code table selected by the code table selecting unit and outputs a bit stream of the encoded data including the re-encoded data. program. An encoded data analysis unit that inputs a bit stream of encoded data of a moving image, analyzes the configuration thereof, and extracts configuration data of the encoded data;
A storage unit group composed of a plurality of storage units each storing the configuration data of the encoded data extracted by the encoded data analysis unit;
A data conversion unit that executes a process of deleting data not used in the decoding process and / or a process of replacing the component data with digital data having a smaller amount of information with respect to the component data of the encoded data;
Re-encoding that reads each component data of the encoded data from each storage unit of the storage unit group, re-encodes the data to be re-encoded, and outputs a bit stream of the encoded data including the re-encoded data A program that causes a computer to function as a part. A bit stream of data that is encoded data of a moving image, and is obtained by re-encoding encoded data of a partial area in the image constituting the moving image by the encoded data re-encoding device according to claim 1. A re-encoded data analysis unit that analyzes the configuration and extracts re-encoded encoded data of the partial region and data representing the image characteristics of the partial region,
A code table group consisting of a plurality of code tables in which the code amount of the code assigned to the encoding target symbol of the encoded data of the partial area is optimized for each image characteristic;
A code table selection unit that selects a code table used for re-encoding from the code table group based on data representing the image characteristics extracted by the re-encoded data analysis unit;
A program that causes a computer to function as a decoding processing unit that decodes the encoded data of the partial area using the code table selected by the code table selection unit and outputs a bit stream of the original encoded data. The encoded data re-encoding apparatus according to claim 5 is used to input a bit stream of encoded data of a moving image in which the configuration data is re-encoded, analyze the configuration, and extract the configuration data of the encoded data Re-encoded data analysis unit,
A storage unit group consisting of a plurality of storage units each storing each component data of the encoded data extracted by the re-encoded data analysis unit;
The encoded data re-encoding device performs processing for deleting data that is not used for decoding processing and / or processing for replacing the structural data with digital data having a smaller amount of information. If so, a data reverse conversion unit that performs conversion processing to return these to the original data,
Read each component data of the encoded data from each storage unit of the storage unit group, decode the re-encoded configuration data, and output the bit stream of the original encoded data, and cause the computer to function as program.

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